Regioselectively substituted cellulose esters and efficient methods of preparing them

摘要

Embodiments of the invention provide regioselectively substituted carbohydrate and polysaccharide derivatives, such as cellulose esters, and methods for preparing them. Particular methods of the invention include deacylation of esters using tetrabutylammonium fluoride to obtain selective substitution at desired hydroxyl position(s) of the ester. Preferred is deacylation of an ester, which shows selectivity for removal of acyl groups from the ester of the secondary alcohols at C-2 and C-3, and which affords cellulose-6-O-esters with high regioselectivity by a simple one-step process employing no protective groups. Inventive regioselectively substituted cellulose esters can be prepared by such methods to obtain esters with the following anhydroglucose repeating units:;wherein R1, R2, and R3 are each independently chosen from a hydrogen atom, and, whether substituted or unsubstituted, branched or unbranched, an alkanoyl group, an aroyl group, and a heteroaroyl group. In embodiments, the alkanoyl, aroyl and heteroaroyl groups can comprise from 1-20 carbon atoms.

主权项

1. A method of preparing a regioselectively substituted ester comprising:
providing or synthesizing an ester from a selected carbohydrate or polysaccharide having a plurality of anhydroglucose repeating units; providing a solvent capable of dissolving the carbohydrate or polysaccharide; providing a tetraalkylammonium fluoride or hydroxide salt capable of selectively deacylating the ester in the solvent; and reacting the ester and the tetraalkylammonium fluoride or hydroxide salt in the solvent for a time and under conditions sufficient to obtain a desired ester product which has been regioselectively deacylated at the C-2 and C-3 positions of the anhydroglucose repeating units, substantially retaining its ester substituent at the C-6 position of the anhydroglucose repeating units.